Figure 5.20-1 VRTC connection

5.20.2RTC Alarm (ALARM)

Pin

 

Name

 

Direction

 

Function

 

 

 

 

 

 

 

50

 

ALARM

 

Output

 

RTC Alarm

The Alarm output is logic output from the module which is supplied from the RTC circuitry block. This block is in turn supplied either from the main supply of the module or from a backup battery if the main supply is not available.

5.20.2.1ALARM Output from the Module

The ALARM time is set by the use of an AT-command. The output is normally at VRTC level and will go low for one second when the ALARM becomes active.

Since the VRTC interface is operable down to 1.1V, transistor circuitry must be used on the host side. It is recommended that integrators use an FET to minimize current consumption. If a suitable FET, operating at the low voltage necessary, cannot be found then bi-polar must be used. The resistors shall be kept as high impedance as possible to minimize current consumption.

LZT 123 1834

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